Copying of opaque originals by contact printing



Dec. 1935- L. P. F. VAN DER GRINTEN 2,026,292

COPYING OF OPAQUE ORIGINALS BY CONTACT PRINTING Filed Sept. 9, 1933 2 Sheets-Sheet 1 1935. L. P. F. VAN DER GRINTEN 2,026,292

COPYING OF OPAQUE ORIGINALS BY CONTACT PRINTING Filed Sept. 9, 1955 2 Sheets-Sheet 2 I i I 1 Y V l V l I V I I l I A A 12 v w v y HUMHYSUUM? P i a P 1 i i I F/Gid a2 .f/ZVfi/Z/O/f V1 7 i i f f ZPiVfikO/i'Zi/ZZG Patented Dec. 31, 1935 UNITED STATES PATENT OFFICE COPYING F OPAQUE ORIGINALS BY CONTACT PRINTING of the Netherlands Application September 9, 1933, Serial No. 688,858 In the Netherlands September 14, 1982 16 Claims.

For making copies by irradiation of originals which are opaque or slightly transparent to light or of originals carrying an image on both sides. such as sheets written or printed on both sides and the like, it is necessary to use rays reflected by the original.

Apart from processes in which a camera--at least an objective-is used, processes are known in which the sensitive material is in contact with or in proximity with the original, that is to say, in which the light first passes through the sensitive sheet and is then reflected from the surface of the original back into the sensitive sheet.

Such processes are for instance described by August Albert in Die Reflektographie etc. Halle 1922. An explanation of these processes is given by R. A. Rciss, Eders Jahrbuch fiir 1903, page 110. The present invention is related to these processes and is called conveniently a process of refiectography" and the copies obtained by the process are called reflex copies.

The art of refiectography is still imperfect. In its application to several photographic processes, such as processes with silver compounds, chromium compounds, diazo compounds, and many others, it has more or less the drawback that seldom or never are fog free or strong copies obtained. Especially if the reflectography is applied in its present form to the diazo type process as proposed by Kogel in the German Patent 302,786, which has the advantage of low costs and the possibility of obtaining directly positive copies, its results are imperfect.

A small improvement is obtained if, as proposed in the French Patent 608,947, there is interposed in the path of the light in proximity to the sensitive material at the side of. the light source a medium which disperses the rays and reflects them to the side of the sensitive material. In this case the radiation remains uniformly distributed but the rays reflected by the original which are not absorbed after passing the sensitive layer are partly reflected again and so retained for the formation of the image, so that a small increase of the strength of the reflex copies isobtained.

It has now been found that in reflectography with the positive diazo type processes the strength of the copies can be increased and other advantages as specified hereafter may be obtained if the radiation which reaches the original does not remain uniformly distributed as in the known processes, but if in any manner care is taken that the radiation during its passage through the space limited by the upper and back surface of the sensitive layer or layers, at least before leaving this space, is divided into small areas of more and of less power.

The present invention therefore substantially differs from the known kinds of reflectography, also from the process described in the above cited French Patent 608,947, because in said patent the homogeneity of the radiation is only temporarily affected in the mat surface through which it passes, after which the diffused radiation is directly homogenized when leaving the matted foil.

The preceding and following use of the term refiectography implies therefore an extension of that idea with respect to its former meaning, more specifically, the present process corresponds with the known reflectography only in its general progress and its final result and is so called only with respect to this superficial similarity.

In order to more clearly set forth my invention, I have shown in the accompanying diagrammatic drawings arrangements illustrating the use of my invention.

In the drawings:

Figure 1 is a diagrammatic section illustrating the prior method of refiectography.

Fig. 2 is a diagrammatic section of a copy obtained according to the prior art.

Fig. 3 is a diagrammatic sectional view illustrating one form of the present invention.

Fig, 4 is a diagrammatic section of a copy obtained according to the form of invention represented in Fig. 3.

Fig. 5 is a view similar to Fig. 3 representing a modified form of the present invention.

Fig. 6 is a diagrammatic section of a copy obtained by executing the form of invention illustrated in Fig. 5.

Fig. '7 is a diagrammatic sectional view illustrating a further modification.

Fig. 8 is another diagrammatic sectional View illustrating a still further modification.

The object of. the invention can be obtained advantageously by the application of locally smaller and locally greater intensity of radiation,

To avoid misunderstanding it is observed that difference in power can exist between radiation of the same intensity if the rays difier in wave length and differ in photochemical power. Such areas of the same or nearly the samev intensity but difierent photochemical power may be obtained for instance by the use of prismatic screens.

Preferably as far as possible directed rays are used. The expression directed or parallel directed radiation is used in this connection in a definite broad sense in such manner that for instance the radiation emerging from a light point or a light source resembling a light point and from a distance not substantially greater than the dimensions of the system subjected to radiarays have only one definite direction. Without the use of further auxiliary means it is difiicult and in some cases practically impossible to obtain a perfectly parallel directed radiation (having everywhere the same direction) of suficient intensity over a large surface. Therefore, for the purpose of the invention a radiation extending for instance from a light point or a point-like light source, such as for instance an arc lamp, if the distance to the system is not too small, may be considered in practice as a considerable step'towards parallel directed radiation, at least in comparison with a diffused radiation.

Instead of a point-like source of light it may be of advantage to use one in the form of a line or band if the division into small areas of more and less power, used for obtaining the reflex copy, is in the form. of lines. In such a case it may be advantageous for the purpose of the present invention, to use a source of radiation in the form of a line or band parallel or nearly parallel to the lines of the division. When using a source of radiation in line or band form as specified above, this radiation must also be considered in the sense of the preceding explanation-at least if the breadth of the source of radiation is not too largeas a parallel directed radiation. It is true that the rays in their projection on a surface vertical to the line like division have a mutually differing direction towards the different distanced lines of division of the surface into which the rays enter, but in these lines themselves and their immediate surrounding in the surface into which the rays enter, only rays having practically one definite direction in the above mentioned projection are active.

For the sake of clearness it will now be explained what is meant in the following specification and claims by the expressions: carrier, sensitive layer, sensitive material sheet".

The expression carrier means the plate-,

sheetor leaf like material upon which or in which the sensitive substance or substances are applied or extended. The function of the carrier is substantially mechanical as indicated by the expression.

The sensitive layer means the space or zone occupied by the substance or substances sensitive to the radiation. The sensitive layer may be outside the carrier, for instance itmay be applied on the carrier. It may, however, also form a part of the carrier, for instance if one or both of the sides of the carrier are impregnated with the sensitive substance, or if the carrier over its whole thickness-at least locally-is impregnated with the sensitive substance.

The "sensitive material is the substance or substances having the necessary photochemical properties for producing the image by selective radiation.

The sheet or "sensitive sheet is the unit, composed of carrier, sensitive material and layer and (if the latter is located outside the carrier prop-, er). If, as described thereafter, the sheets carry screens, these screens are considered as belonging to the sheet, therefore to the unit. Possible interruptions of the sheet or its parts (for instance 5 perforations) are also considered to belong to the sheet.

Fig. 1 of the drawings shows the old method without division of the radiation. The radiation passes the sensitive layer E and impinges on the 1 original 0. The black parts of the original are indicated by a cross-hatching and absorb the radiation. The white parts reflect it. Above the black parts the sensitive material, preferably diazo compound, is decomposed only by the direct 15 radiation. Above the white parts, however, it is decomposed by the direct and the reflected rays.

As only a relatively small part of the rays are reflected, because most of the rays are already absorbed before impinging on the original, and of 20 the impinging rays only a part is reflected, the photochemical decomposition above the black parts is only slightly less than above the white parts. Therefore, there remains only a small part of the sensitive material above the black 25 parts, so that only weak copies are obtained (Fig. 2). In Fig. 2, E shows the developed image layer,

The effect according to the invention is obtained in a simple manner if the radiation is caused to pass through a socalled screen which 30 may be applied between the source of radiation and the sensitive sheet, preferably in the immediate proximity of the sensitive sheet, possibly in direct contact with it. This screen may be a covering screen i. e. of varying opacity, or a lenticu- 35 lar, prismatic or any similar screen which is suitable for subdividing a uniform irradiation into small areas of lower and higher photochemical power.

Fig. 3 explains the invention. The radiation 40 passes through the screen R before it reaches the sensitive layer E. The screen divides the radiation in areas which pass undiminished through the non-covered parts I) of the screen and areas below the covering screen parts a, by which the 45 radiation is stopped wholly or substantially. The radiation passing through the opening b impinges on the original. The cross-hatched black parts of the original do not reflect and absorb the radiation. The sensitive layer is decomposed only 50 in the path of the rays. In this way, above the black part of the original a screen structure is formed in the sensitive layer, but below the parts a of the screen the sensitive layer is unchangedand may be developed. 55

The white parts of the original, however, do reflect the impinging rays. The reflected rays decompose the sensitive material below the covering parts a of the screen. The sensitive material above the white parts of the original is com- 60 pletely decomposed thereby. Therefore, the

' image is obtained of which the image layer E is shown in Fig. 4. It is clear that the force of the image is much greater than in the case of Fig. 2. 65 When using a separate covering screen it has been found that in certain cases better results are obtained the more the screen surface-at least at the side directed to the sensitive layer-is reflective, for instance like a mirror. Reflectivity 70 of the coveringparts of the screen towards the source of radiation has the additional advantage of reflecting the intercepted rays back towards the source of radiation so that-if this is provided with a reflector, or if for instance-the process is 75 the image which are parallel with the screening. If this drawback occurs it may be removed by a suitable position of the screening or by the use of a different screen.

In general, it has been found that it is advantageous to work with screenings of such form that the zone of the covering parts which is at the greatest distance, or the greatest average distance from the edges of these parts, is substantially parallel with these edges. If the coarseness is small this feature is of minor importance.

The screening may be obtained in several ways: photographically, by mechanical action, by spraying, atomizing, perforating etc. Total or partial perforation (that is to say a perforation of part of the thickness of the layer or sheet) may be applied with advantage to the sensitive sheets them.- selves.

The sensitive material namely diazo compounds changing or losing its absorbing power when subjected to radiation the screening of the sheet or th e layer may advantageously be obtained by a preliminary radiation through a screen, in which case the sensitive sheet takes over the form of the screening of the screen used during the preliminary radiation. In this preliminary radiation preferably screens are used which do not reflect towards the sensitive sheet. The radiation is directed as much as possible and an absorbing back ground is used. The layer obtained may be used without screen or screening.

For the manufacture of r'efiex copies usual auxiliary means, such as radiation with definite kinds of light, radiation through definite filters etc. can also be combined with the present process, but according to the present invention, practical copies of suificient strength are obtained, also without such auxiliary means, even from originals having dark parts which are not black, but for instance colored, such as originals written or typed with colored ink or the like, and which when copied by means of a radiation through the original will yield only moderate or bad copies. Itis one of the advantages of the present invention that rays of short wave lengths may be used, such rays being preferably avoided in the known reflex copying processes. This feature of the present invention is of particular advantage in that better refiex'copies can now be made by using those processes which are sensitive substantially only for rays of shorter wave length, such as processes with diazo and similar compounds.

As suitable carriers for the light sensitive materials every suitable transparent carrier may be used. Preferably carriers of a uniform structure having little influence on the direction of the rays and with highest transparency such as for instance glass, celluloid, cellophane (registered trade-mark), gelatine foil and the like are used, but also transfer papers, transfer linen and the like of sufiicient transparency may be used.

The sensitive layers may be applied on the carrier on one or both sides and may also be present in the whole mass of the carrier. Best results, however, are obtained with carriers provided on one side only with sensitive material the sensitive side being then turned away from the original and therefore turned to the screen.

The invention may be applied with the positive diazotype process by which positive images in black and different colors may be obtained directly. The quantity of sensitive, color forming or covering forming material in the unit of surface is also a factor for determining the strength of the image.

Example 1 A glass plate is covered on one side with a refleeting layer of silver foil which is then screened to form a line screen of a coarseness of 0.2 and a covering factor 0.8. The sensitive sheet consists 5 of a gelatine foil prepared on both sides with an alcoholic solution of diazo-l-dimethylamino-4- methyl-Z-benzene.

The original is a typed letter. After exposure to directed radiation of an arc lamp the film is developed in an alkaline solution of phloroglucinol to which salts are added. A positive image is obtained of greater strength than the im age which under similar conditions would have been obtained with a difiused radiation or without a screen.

Example 2 On a cellulose film of 0.06 mm. thickness and prepared on both sides with a diazo-l-dimethyl- 20 amino-4-benzene solution a line screening with a coarseness of 0.5 and covering factor 0.8 is applied on one of the sides.

The screening material which is printed. on the one side may be composed in the following 25 manner: take 100 parts of water, 6 parts of casein,

6 parts of sugar and add so much aluminium powder that sufiicient covering power is obtained.

Between the sensitive sheet and the original a transparent intermediate layer of 0.1 mm. thick- 30 ness is placed.

Radiation is carried out with a mercury vapour lamp in such manner that the screened side is turned to the source of radiation. After the irradiation the film is developed in an alkaline 35 solution of an azo component. If the screen material is not already loosened by this development, the surface may be rubbed so that the screen layer is removed. A positive image is obtained of greater strength than the image which 40 would have been obtained under similar conditions without a screen.

If before its use the sheet provided with an absorbing back ground and with the screen side turned to the source of radiation is subjected to 45 a preliminary radiation, the ultimate user may use a shorter time of radiation for obtaining the desired result. This preliminary radiation is effected preferably with a directed radiation.

Example 3 A celluloid film of 0.16 mm. thickness is provided at one side with cylindrical lenses which are applied in the material itself.

The radius of the cylinders is about 0.03 mm. 55 The mutual distance of the focus lines is 0.04 mm. This distance is called in this case the coarseness of the screening. This is therefore 0.04. The nonscreened side is provided with a layer of paradiazo-diphenylamine. The film is now applied 60 with this side against a cutting from a journal and exposed to radiation.

During the radiation preferably a black absorbing back layer is applied against the back side of the cutting. After radiation with are light the a development takes place in a suitable developing machine by applying a thin layer of an alkaline solution of an azo component. A positive image is obtained.

The covering factor is preferably taken as large as possible by applying the sensitive layer in or near the focus of the lenses and by using directed radiation.

Example 4 A transparent carrier is provided in its whole mass with diazo 1 di-ethylamino 4 benzene.

The sensitive sheet thus obtained isbrought in direct contact with a nonreflective screen of a:

Example 5 A transparent foil covered on both sides with paradiazodiphenylamine is perforated in such manner that oblong openings are obtained with a length of 1 cm. and a breadth of 0.1 mm. with intermediate spacesof 0.1 mm. The thus obtained screening has a coarseness of 0.1 and a covering factor of about 0.5. In order to diminish the strength of the foil as little as possible the series of lines may be shifted with regard to each other.

The prepared foil is put on the original and irradiated with directed radiation of an arc lamp. After development with an alkaline azo component a positive image is obtained.

I claim as my invention:

1. A process for making positive reflex copies of an original, comprising applying on the original a sheet containing a diazo type layer sensi tive to irradiations, and passing a'plurality of small separated distinct beams of irraditions through said layer of sensitive material onto the original.

2. A process for making positive reflex copies, comprising the steps of applying on an original a sheet containing a layer of sensitive diazo compounds, subjecting the original to a radiation through said sheet, and subdividing said radiation before it has passed through said layer of sensitive material into small areas of lower and higher photochemical power.

3. A process accordingto claim 2, in which directed irradiation is used.

4. A process for making positive reflex copies, comprising the steps of applying on an original a sheet containing a layer of sensitive diazo compounds suitable for the formation of a positive image of the original, subjecting the original to a radiation through said sheet and locating a screen between the source of radiation and the image-forming layer of sensitive diazo compound.

5. A process according to claim 4, in which a covering screen is used.

6. A process according to claim 4, in which a lenticular screen is used.

'7. A process for making positive reflex copies, comprising the steps of applying on an original a sheet containing a layer of sensitive diazo com- 5 pounds suitable for the formation of a positive image of the original, subdividing the part of the sheet between the image-forming layer and the source of radiation into small areas of substantially high transparency for active rays separated by areas of low transparency, and subjecting the original to a radiation through said sheet.

8. Process according to claim 7, in which the sheet is provided with a screen.

9. Process according to claim 7, in which the 5 sheet is provided with a removable screen. I

10. Process according to claim 7, in which the surface of the sheet has the form of a lenticular screen.

11. A process for making positive reflex copies, comprising the steps of applying a sheet containing a layer of sensitive diazo compounds suit able for the formation of a positive image of the original, screening said layer of sensitive diazo compound so as to present small areas substantially free from diazo compound separated by areas containingdiazo compound, and subjecting the original to a radiation through said sheet.

12. Process according to claim 11, in which the sheet is provided with a screen between the layer containing the diazo compound and the source oi radiation. a Q

. 13. A sensitive sheet for preparing positive reflex copies, comprising a layer of diazo compounds, presenting small area's substantially free from diazo compounds separated by areas containing diazo compounds. 1

14. A sensitive sheet for preparing positive reflex copies, comprising a layer of diazo compounds, presenting small areas substantially free 40 from diazo compounds separated by areas containing diazo compounds, and a screen associated therewith.

15. Process for obtaining sheets to be used for making positive reflex copies, comprising combining a sheet containing a layer of sensitive diazo compounds with a screen, subjecting the sheet to a uniformradiation with said screen located between the sensitive layer and the source of radiation, until a substantial part of the diazo compounds behind the transparent parts of the' screen is decomposed, and then removing the screen, said radiation being such that it has substantially the same power throughout its entire surface.

16. Process according to claim 15 in which a directed radiation is used.

LODE'WIJK PIETER FRANS vm nan GRINI'EN. 

